Field of the Invention
The present invention relates to a gas distributor used in a manufacturing process of a semiconductor device or a liquid crystal display device.
Description of the Related Art
Generally, a semiconductor device or a Liquid Crystal Display (LCD) is manufactured by depositing a film by depositing gas and the like on a wafer or glass which is a substrate. For example, the semiconductor device and the LCD is manufactured by repeatedly performing a process of forming a film by depositing gas on a substrate, and a lithography process, an etching process, and an ion implantation process for forming a desired pattern. In this case, the process of forming the film includes Chemical Vapor Deposition (CVD), metal deposition, and the like, and particularly, in the process of the CVD, a source gas for depositing is distributed on a substrate loaded in a chamber, and thus a fine and thin film is formed on the substrate. In this case, the factor most affected on the quality of product is to obtain deposition uniformity.
Accordingly, in the process of the CVD, it is important to uniformly distribute the source gas on the surface of the substrate, and to achieve the object, gas distributors of various structures (or referred to as ‘shower head’) have been proposed.
FIG. 1 is a cross-sectional view showing a configuration of a gas distributor according to the related art.
Referring to FIG. 1, the gas distributor 10 of the related art is a plate having a predetermined thickness throughout its entirety, and a first process gas flow path 11 and a second process gas flow path 12 are formed in the plate. In this case, process gases are separately supplied through each of the process gas flow paths to a chamber. A reference number 13 denotes a cooling water flow path through which cooling water flows.
Forming the gas distributor of the related art is performed through a variety of forming processes according to the shape of a hole or the flow path defined in a plate of a predetermined thickness.
For example, in forming the first process gas flow path 11, a first gas flow path 11a is formed in parallel to the plate by drilling a circular hole of at least 300 mm in diameter by using a gun drill, and then a second gas flow path 11b (around 1 mm in the gap) is formed in a vertical direction to the plate by performing wire electric discharge machining such that the second gas flow path 11b communicates with the first gas flow path 11a. 
Meanwhile, the second process gas flow path 12 (normally around 2 mm) is formed in a vertical direction to the plate by performing electric discharge machining.
The cooling water flow path 13 is formed by using the gun drill.
Accordingly, the gas distributor to feed different kinds of process gases is manufactured through various forming processes such as the previously mentioned gun drilling, wire electric discharge machining, and electric discharge machining, considering the positions, shapes, and sizes of the flow paths that will be formed in the plate of a predetermined thickness, which makes a forming process both complicated and expensive.
In addition, forming the flow paths in the plate is limited in terms of the range of forming, and particularly, gun drilling, electric discharge machining, and wire electric discharge machining can form only holes and gaps of linear shapes, and thus, even when the shapes of the flow paths require changing in consideration of gas flow, the limitation of forming makes it difficult to change the shapes of the flow paths.
For example, the first gas flow path 11a and the second gas flow path 11b are formed by gun drilling and wire electric discharge machining, respectively. In this case, when two flow paths meet, bordering surfaces are orthogonal to each other, which causes turbulences between the bordering surfaces. Accordingly, the turbulences are produced at the bordering surfaces A that are orthogonal to each other, thereby making the resistance of the gas flow considerable.
Furthermore, even when the shapes of the flow paths require changing so as to change flow rate, pressure and velocity which are important factors in controlling the process gases flowing through the flow paths, the forming process mentioned above can change only shapes of holes, thereby causing problems due to the limitation in controlling the process gases.
Next, forming by means of wire electric discharge machining is performed by penetrating the plate based upon the characteristics of forming thereof, thereby often causing undesired results.
For example, because it is generally required to form the second gas flow path 11b as a small hole of about 1 mm gap, the forming of the second gas flow path 11b is performed by wire electric discharge machining in the related art. In this case, the hole B is formed through an upper part of the first gas flow path 11a based upon the characteristics of forming. However, such an undesired hole may cause the first gas flow path and the second gas flow path to interrupt gas flow due to by-products produced by the flow of two process gases since the first gas flow path and the second gas flow path communicate with each other.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.